An athletes ability to run a fast 40 yard dash, dunk a basketball, kick a field goal, or take down an opponent in hand to hand combat are all highly determined by explosive strength. By definition, Explosive Strength refers to the ability to exert strength or force as rapidly as possible in a given action (Siff). Explosive Strength is dependent on Rate of Force Development (RFD), which simply stated means the speed at which force can be produced.
Before taking the necessary steps in your training to improve explosive strength you must first determine if you already have established a sufficient base of Relative Strength for the given task. Relative strength is the maximum force exerted in relation to body weight or muscle size. While no specific guidelines exist as to how strong is “strong enough” before the law of diminishing returns comes into play, it's important to note that I've witnessed athletes who have participated in plyometric (jumping) programs making literally no improvement in explosive strength.
How can that be? After all, the Principal of Specificity implies that in order to become better at a particular exercise or skill, you must perform that exercise or skill. For a real world example of this, consider Lance Armstrong, possibly the best long-distance bike rider in the world: although he certainly has a lot of stamina, he ended up running a three hour marathon in his first outing. Why? Because of the Principal of Specificity - he hadn't done enough running, endurance notwithstanding.
Following that logic, you'd think that to improve your vertical jump you must simply do that in training. But this is only one small piece of the puzzle. It's possible that in the prior scenario I have mentioned (in which there was no improvement in vertical jumping ability despite the implementation of plyo jumps training) the athlete did not possess adequate relative strength. This would have enabled him to apply more force, and ultimately to jump higher. For this individual it would be important to have a look at which muscles are responsible for jumping ability and develop a plan to strengthen those obviously weak areas. In other words, a guy who is squatting 100lbs, is not going to get a significantly better vertical jump simply by adding some jumps to his training; he's just too weak to jump very high.
Since jumping uses virtually every muscle in the body it would be important to implement a resistance training program, that includes the entire body. Don't believe me? Some estimates indicate that the deltoid (shoulder) muscle contributes as much as 10-15% of the height attained by a vertical jump (hint: try jumping with your hands clasped behind your back and compare it to the height you can get by allowing your shoulders to swing your arms upwards, and you'll see what I mean).
To break things down further it would be imperative to identify the prime movers in the given task (in this case the vertical jump) and put extra focus on improving strength in those areas. In the vertical jump example this would include the hamstrings, glutes, quadriceps, spinal erectors and abdominal muscles. Just to note: research has shown calves to offer very little contribution to vertical jumping ability. The movements, which target the aforementioned areas, would be variations of the squat and deadlift along with unilateral work such as several of the lunge and step-up variations.
On the opposite side of the spectrum I have seen improvements in squat and deadlift performance illicit no improvement sprint or vertical jump performance. I believe there is a “ceiling effect” here as well where once an athlete is “strong enough” for a given task becoming stronger will no longer yield any benefit; you reach the Law of Diminishing Returns once again. In this case,r the athlete must improve the speed at which he or she can apply force in order to yield improvement in explosive strength activities.
Improving Explosive Strength is as mental as it is physical, and by this I mean that the “intent” to move your body or an object quickly is of utmost importance. While your mind might wander during a marathon, if this happens during a 100m sprint, you'll find yourself in last place before you know what happened. This is due to the role of the Central Nervous System, which acts as the control center between your brain and muscles. It's not enough to give 100% physical effort, you need to give a 100% mental effort too.
Lower body exercises that may produce improvements in RFD would include but are not limited it to:
- Box Jumps
- Standing Long Jumps
- Vertical Jumps
- Squat Jumps
- Kneeling Jumps
*These movements may be done with or without extra external load
Upper body exercises that may produce improvements in RFD would include, but are not limited to:
- Medicine ball throws for height or distance (against a wall or floor)
- Plyo pushups (or clapping pushups)
- Sledgehammer hits to a tire
When training to improve Rate of Force Development it is important to perform those movements in a non-fatigued state. First thing in the workout is usually best due to the requirement of being able to execute each movement with the same amount of speed/effort. This would not be possible in a fatigued state due to a decline in technique that may occur. Ground contact times increase along with likelihood of injury. Complete rest between both sets and each individual repetition will ensure you’re getting the most out of your workout.
Example of Programming for Lower Body RFD
- Box Jumps or Kneeling Jumps 5 x 3-5
- Standing Vertical Jump 5 x 3-5
Example of Programming for Upper Body RFD
- Medicine Ball Throws
- Chest Pass 5 x 10
- Overhead throw 5 x 10
- Plyo Pushups/”Clap” Pushups 5 x 5-10
- Sledgehammer Hits into Tire 5 x 10